The skeleton structures of β-carboline, dihydro-β-carboline and tetrahydro-β-carboline widely exist in natural products and drug molecules. Harmine and tetrahydroharmine belong to β-carboline and tetrahydro-β-carboline alkaloids respectively and are representative compounds of harmala alkaloids. Harmine was first separated from P. harmala L. This alkaloid shows cytotoxicity to leukemia cell lines HL60 and K562. Tetrahydroharmine is a fluorescent molecule separated from Malpighiacease plant Banisteriopsis caapi. This compound has weak inhibition to the re-uptake of 5-hydroxytryptamine. Harmaline is an agonist of the central nervous system and a reversible inhibitor of monoamine oxidase (MAO-A).

Currently, the research on β-carboline, dihydro-β-carboline and tetrahydro-β-carboline and substances similar to them focuses on anti-tumor, killing of human parasites and monoamine oxidase inhibitors. However, as far as we know, no document reports the activity of β-carboline, dihydro-β-carboline and tetrahydro-β-carboline and substances similar to them against plant viruses, and little was reported on their bactericidal activity and insecticidal activity. In the aspect of bactericidal activity: Fu Haibo et al from Gansu Agricultural University researched and found in 2007 that the extracting solutions of P. harmala L. in different solvents all have certain inhibiting effect to spore germination of four kinds of pathogenic bacteria, including Botrytis cinerea, Fusarium oxysporum, Alternaria solani and Cladosporium cucumerinum Ellis et Arthur, and their EC50 is 0.060, 0.199, 0.105 and 0.223 g/mL respectively (Fu Haibo, Ding Defang, Zhao Hongmei, Yang Shunyi, Grassland and Lawn, 2008, 1, 44-48); in 2007, Wen Ren et al from Fudan University reported derivatives with a structure of 1-(3-indol)-1,2,3,4-tetrahydro-β-carboline and researched the in vitro activity of these derivatives against Pyricularia oryzae (CN101020688); in 2011, Zhang Yaomou et al from South China Agricultural University reported compounds with a structure of β-carboline-3-oxime ester and meanwhile studied the inhibitory activity of these compounds against Colletotrichum musae, Colletotrichum gloeosporioides and tomato late plight (Lu Shaoying, Zhang Yaomou, Synthetic Chemistry, 2011, 19 (6), 769-772); in 2012, this research group again reported compounds with a structure of 1-p-trifluoromethylphenyl-β-carboline-3-carbonyl bishydrazide, but the quantity of the compounds was small and their bacteriostatic activity against Rhizoctorzia solani was tested only (Cai Ying, Huang Jianfeng, Zhang Meidan, Zeng Yong, Zhang Yaomo, Synthetic Chemistry, 2012, 20(6), 736-739.). In the aspect of insecticidal activity: in 2005, Zhao Xiaomeng et al from Beijing University of Agriculture reported the contact activity of the ethanol extract, chloroform extract and water extract of the overground part of P. harmala L. in the growing period against Myzus persicae, Macrosiphum rosivorum and Tetranychus cinnabarinus. The result is that their contact activity against spider mites is all above 95% at concentration of 10 mg/mL, and that against two kinds of aphids is above 70% at concentration of 10 mg/mL (Zhao Xiaomeng, Zeng Zhaohai, Chinese Agricultural Science Bulletin, 2005, 21(4), 278-279); in 2010, Zhong Guohua et al from South China Agricultural University reported the insecticidal activity of 1,3-disubstituted β-carboline and tetrahydro-β-carboline derivatives against culex pipiens larvae and Lipaphis erysimi. To be specific, the LC50 of the compounds with a structure of 1-phenyl substituted β-carboline and tetrahydro-β-carboline-3-methyl ester against culex pipiens larvae is 20.82 mg/L and 23.98 mg/L respectively, and the LC50 against Lipaphis erysimi is 53.16 mg/L and 68.05 mg/L respectively (Zeng, Y; Zhang, Y M.; Weng, Q. F.; Hu, M. Y.; Zhong G H. Molecules 2010, 15, 7775-7791).